Mario is exploring a planet. Then a shadow flies over him. Samus Aran's ship had flown over him. Samus Aran gets out of the ship.

Mario: Lets-a-go!

Samus Aran aims her arm cannon at Mario.

FIGHT!

Samus Aran fires a missile at Mario, but Mario jumps over it and hits Samus Aran with his hammer. He then punches Samus Aran repeatedly. Samus Aran then jumps away from Mario and goes into ball form and rolls under Mario. Mario soon realizes that Power Bombs are underneath him, but it's too late. They explode. Mario gets out a Fire Flower and becomes Fire Mario. He shoot fireballs at Samus Aran, who counters with missiles. Fire Mario then jumps behind Samus Aran and shoots a fireball at her, but Samus Aran counters with a missile. She then fires another missile, but Fire Mario jumps over it and behind Samus Aran. He then hits her with his hammer repeatedly. Samus Aran jumps away from Fire Mario and fires a missile at him, draining his Fire Flower. Mario growls in anger. He then gets out an Ice Flower and becomes Ice Mario. Ice Mario tries to freeze Samus Aran, who counters with her arm cannon. Ice Mario then jumps behind Samus Aran and tries to freeze Samus Aran, but Samus Aran jumps over the ice and fires a missile at Mario, draining his Ice Flower. Mario gets even angrier.

Mario: That's-a-it!

He then gets out a Mega Mushroom and becomes Mega Mario. He raises his fists to crash them down on Samus Aran, but Samus Aran dodges. He grabs her and looks at her before throwing her away. Mega Mario then runs at Samus Aran to crush her. But Samus Aran fires a missile at Mega Mario's eye, making him scream painfully. While Mega Mario is in pain, Samus Aran runs to her ship. She gets into it. Mega Mario sees the ship and runs at it to destroy it. But the ship is too high. Soon he shrinks to normal size. At this point, Mario has had it.

Mario: I WILL DESTROY-A-YOU!

The ship then flies at Mario. Mario jumps on it. He makes a hole in it and fights Samus Aran. He hits her with his hammer repeatedly.He then grabs Samus Aran's leg and throws her away. He then pilots the ship, making it fly to Earth. But Samus Aran shoots a missile at him. She then grabs Mario and leaps out the hole in the ship and throws him back to the planet. Mario gets out a Cape Feather and becomes Cape Mario. He flies after the ship. Soon the ship enters Earth's atmosphere. Cape Mario flies into the hole in the ship and gets out the Metal Cap and becomes Metal Mario. Samus Aran then blasts another hole in the ship and leaps out of out. Metal Mario also leaps out of it. The two fight on the ship. Metal Mario punches Samus Aran. Samus Aran jumps behind Metal Mario and fires her arm cannon at him. The ship soon crashes on the ground, destroying it and making Samus Aran and Metal Mario fly into the air. They continue fighting in the city. Samus Aran fires her arm cannon at Metal Mario, but Metal Mario jumps behind her and punches her repeatedly. Samus Aran turns around and fires a missile at Metal Mario. She then jumps behind Metal Mario and fires her Ice Beam at Metal Mario, freezing him. Samus Aran then fires her Zero Laser, obliterating the frozen Metal Mario.

This was close, Mario's Mini Mushroom would make him lose this battle. Mario is durable, but Samus Aran is on par with Dark Samus, who can survive a planet explosion. Also, Samus Aran's Ice Beam was a problem. She also bests him in weaponry. While Mario has fought formidable enemies, so has Samus Aran.